Shrink sleeves are used to cover perforated rolls, in the nature of couch rolls. The covered roll is placed in direct contact with a fiber mat for the purpose of extracting moisture from the mat by both pressure and suction.
An alternative application of a covered roll is to collect fibrous material from a drum or vat, the fibrous material being held to the covered roll by suction. As the surface of the covered roll leaves the vat, the fibrous material is doctored off by a doctor blade, onto a belt.
Due to the critical nature of the processes in which these covered rolls run, the covers cannot have a seam. It is not possible, for example, to weave a flat fabric, seam it and then join the seam as the fabric is wrapped around a roll. Therefore, shrink sleeves have been woven as endless pieces. To install these shrink sleeves requires the dismantling of a machine, removing a roll, sliding the woven shrink sleeve over the roll and then rebuilding the machine with the covered roll. At the same time, steam has to be applied to the fabric to cause it to shrink, to thereby fit tightly on the roll. The application of steam involves fitting a temporary steam shower over the roll and then removing the steam shower before the machine starts up as the position of the shower interferes with the operation of the machine.
Some problems presently encountered by the use of endless woven shrink sleeves are that the sleeves: 1) suffer from premature wear, 2) require 14 to 16 hours to install the woven endless sleeve, which is excessive, and 3) the cost of the woven endless sleeve has proven expensive.